The internal pressure inside an unopened bottle of champagne or sparkling wine can be as much as 100-150 psi, especially if the contents of the bottle are warm or if the bottle has been shaken. Because of this pressure, a champagne cork can be propelled from the bottle at a velocity of well over 120 Kph. A cork traveling at such a speed can seriously injure the person that is opening the bottle as well as individuals that are standing nearby. The human eye is especially vulnerable to injury because the cup shape of the eye socket mirrors the cup shape of the typical champagne cork. Individuals standing near windows or mirrors that can be shattered by the force of the flying cork are also vulnerable to injury from flying pieces of glass. To make matters worse, as soon as the shrink wrap and wire restraining device are removed from the champagne or sparkling wine bottle, the corks can explode spontaneously. In such an instance there is no opportunity for the person opening the champagne to place a towel over the top of the bottle as a means of providing some protection against the dangers of the explosive release of the cork.
The problem of premature or inadvertent explosive release of champagne corks is exacerbated by the fact that many lower priced champagnes and sparkling wines are closed by molded plastic corks. Plastic corks possess an even greater tendency than natural corks to become dislodged as a result of internal pressure in the bottle. Wetness on the glass surface of the bottle as a result of condensation or seepage of the contents can also reduce friction between the surface of the glass and the surface of the plastic cork.
In an attempt to solve the problem of premature or inadvertent release of champagne corks, U.S. Pat. No. 4,474,302, issued October, 1984 to Goldberg, et al., discloses a closure device (referred to herein as the '302 device) that employs a helical tether strip of rounded cross-section that is integrally connected to a cap-plug portion and an outer retaining collar which fits over the neck of the bottle. When the tear strip is torn away, a helical tether strip remains interconnecting the plug or cork and the retainer collar. The cork or plug can thus be easily released from the bottle, and yet is restrained from flying free. In most instances such restraint is sufficient; however laboratory tests of the device showed that the helical tether would sometimes break when the cork was released from the bottle.
U.S. Pat. No. 4,564,114, issued Jan. 14, 1986 to Cole, discloses an improved tethered safety closure device (referred to herein as the '114 device) that is similar to the '302 device but differs from it in that the '114 device employs a tether of rounded cross-section that is folded upon itself, thereby making it stronger than the helical tether of rounded cross-section of the U.S. Pat. No. 4,474,302.
The present invention discloses a new tethered safety closure device that utilizes the folded tether design of the '114 device, but improves upon it by replacing the rounded cross-section tether portions with tether portions of rectangular cross-section. Surprisingly, unlike the rounded cross-section tethers, the rectangular cross-section tether portions do not significantly distort or collapse when the molded closure devices are removed from the mold or when they are initially placed on the bottles of champagne or sparkling wine. In addition, the closure device of the present invention incorporates an annular shoulder on the device's retainer collar as a partial means for removing the finished closure from the mold of the present invention.
U.S. Pat. No. 4,541,795, issued Sep. 17, 1985 to Cole, discloses a mold that is especially suited for making the tethered closure devices of the '302 and the '114 patents. As the '795 mold patent points out, the molding of a plastic closure device is typically carried out in an injection molding machine. Such machines usually employ a plurality of die or mold plates and, in appropriate cases, a movable core. The mold plates and core move once the piece is molded to separate and enable removal of the molded device from the mold.
Where, as is the case with the '302 and the '114 devices, and the improved plastic closure device of the present invention, there are two portions (i.e., a plug portion and a retaining collar) that extend substantially coextensively and coaxially with each other, the molding procedure and mold may be extraordinarily complex. With a simple cylindrical device, a collapsible mold core may be provided making removal of the molded part after molding relatively easy. However, in the present case, a collapsible core is not practical due to the presence of the plug portion that is coextensive and coaxial with the surrounding cylindrical collar. This problem is exacerbated in the present instance because the lower portion of the restraining collar contains an annular recess (for mating with a retaining ring on the bottle or other container) that has deep undercuts on both its inner and outer surfaces. Such undercuts make it very difficult to remove the closure device from the mold once the molding process is complete.
The mold of the U.S. Pat. No. 4,541,795 (referred to herein as the '795 mold) has multiple moving parts. It addresses the problem of the severe undercuts on the retaining collar by employing movable mold segments which include a gripping portion or means. The gripping means retain the closure device while the mold's outer core is extracted from the cavity between the plug portion and the inner surface of the closure. Once the core is extracted the gripping means separate along with the remainder of the mold segments to allow removal of the molded device.
Unlike the '795 mold, the mold of the present invention has relatively few moving mold parts. In addition, the mold has a novel stripper means to remove the molded closure device from the mold's outer core means. As those skilled in the injection molding arts will appreciate, the fact that the mold of the present invention has few moving parts makes it possible to have more cavities per mold (for the size of the mold), which in turn makes it possible to mold more closures per mold cycle. In addition, the design of the mold of the present invention permits placement of more cooling channels close to the molding surfaces. This results in greater cooling of the newly molded devices, which in turn shortens molding cycle times. Consequently, closure devices can be made faster and cheaper in the mold of the present invention than they could be made in the '795 mold.